1. Field of the Invention
The present invention relates to hydrants, and more particularly to a new and improved ejector purge assembly for draining water from the casing of a yard hydrant to prevent contamination of the water supply and front damage to the hydrant.
2. Description of the Prior Art
Yard hydrants are often used to supply water from a source below the frost line. It is undesirable for a yard hydrant, after being used, to retain water within that portion of the hydrant casing above the frost line. Such retention of water in the casing could result in damage to the hydrant if the water freezes. Moreover, residual water could become contaminated.
To overcome these problems many prior art hydrants include a bleed opening leading from the bottom of the hydrant casing to a below grade gravel pit. When the hydrant is turned on, the bleed passage is closed by the main valve; and once the hydrant is turned off, the bleed hole is opened allowing water to drain from the casing. An example of such a typical prior art yard hydrant is disclosed in U.S. Pat. No. 3,070,116.
One disadvantage with such an arrangement is that ground water contaminants can enter the hydrant casing through the bleed line resulting in unsanitary water that, when the hydrant is again turned on, can be mixed with the water supplied from the spout or head of the hydrant. Accordingly, a current goal in the industry is to provide a yard hydrant that is both frostproof and sanitary.
One solution to the problem of attaining a frost proof and sanitary yard hydrant includes a bleed line that extends through an above grade siphon that includes a check valve and air gap. The air gap serves to prevent migration of contaminants through the liquid media after draining of the casing and prior to the next operation of the hydrant. A hydrant of this type is disclosed in U.S. Pat. No. 3,858,599.
Another solution to the problem of providing a hydrant that is both sanitary and frostproof is a hydrant having a casing with a reservoir below the frost line into which supply water drains when the hydrant valve is closed. When the hydrant is next opened, the reservoir is emptied through the hydrant spout by venturi action. Such a hydrant is disclosed in U.S. Pat. No. 3,885,585. One disadvantage with this prior art hydrant is that water can be held in the reservoir for extended periods of time after which it is ejected from the spout. This water can become stale or contaminated due to the extended period of storage. In addition, a restriction, such as that provided by a long hose or a vacuum breaker, at the spout can interfere with the intended operation of the hydrant by rendering the venturi action ineffective.